AUSTIN, Texas (Reuters) - Ferrari's Sebastian Vettel put talk of a contract extension to one side on Thursday and emphasised that his main priority was to help the team build a better car to take on dominant Mercedes.

Formula One's most successful and glamorous team have yet to win this season, after four-times world champion Vettel enjoyed three victories last year, and are third in the standings behind Red Bull.

Vettel, 29, will be in the final year of his contract next season, when the rules undergo a major shakeup, but he said there was no hurry to get a new deal wrapped up.

"I think we are all fairly busy at this time to focus on the four races that are left and focus in particular to prepare for next year so I think that's where...the main focus lies," he told reporters at the U.S. Grand Prix.

"I don’t think it’s that important to look into details...my contract is all fine for next year. So with a lot of things happening back at the factory, back in Maranello...we’re very, very busy and that’s where I want also the focus to be."

Vettel's 37-year-old Finnish team mate Kimi Raikkonen, the 2007 champion, is also out of contract at the end of next season and is expected to leave with several candidates in the frame to replace him.

While Vettel is seen as a long-term prospect for the Marenello team, Ferrari principal Maurizio Arrivabene said recently that the German had to earn his place and a decision would be made next year on 2018.

"Each of us has goals," he told Sky Italia this month. "So it is only right that anyone, no matter who it is, earns their place and their salary."